1. Technical Field
The present invention relates to hybrid work machines where an engine is assisted by an electric motor.
2. Description of Related Art
In recent years, more and more work machines have become hybrid in order to improve the energy efficiency of work machines. In hybrid work machines, it is possible to efficiently drive a hydraulic working element by driving a hydraulic pump with small engine output by assisting an engine using an electric motor that is driven with electric power from an electric energy storage unit. (See, for example, Japanese Unexamined Patent Publication No. 2009-261096 [Patent Document 1].)